inherited from the mother, along with a Y chromosome from the father. So, males don’t have another X chromosome to cover up the infected genes. Women on the other hand, have two X chromosomes and are more likely to not show any symptoms of the abnormal gene.Two female patients with all the symptoms of X-linked EDA led Dr. Kere, Dr. Srivastave, and other colleagues to the discovery of this gene. Earlier work by Jonathan Zonana, identified an unusual chromosomal rearrangement in one of the girls. The X chromosome had been sheared in two, with one piece sticking to the end of chromosome 9 and the remainder forming a truncated X. A similar X translocation was identified by other investigators in the second girl. Although the break points occurred in slightly different locations, both destroyed the function of the EDA gene. This indicated that the breaks occurred within the region of the chromosome that contains the gene. In other disorders where X translocations have been identified as the cause, the normal X chromosome is inactivated, leaving no functional copy of the gene. The disorder is the same as it would be in males.7Several different studies following the inheritance pattern of the known genetic markers on the X chromosome have narrowed the position of the gene to a region called the “Xq12-q13.1” Once this region had been identified, the DNA sequences of genes needed to be studied.2In one of the studies, scientists identified a gene in the region of the X chromosome that contained the molecular code to produce a 135-amino acid protein. This protein has a structure compatible with a transmembrane molecule, a protein that is part of the cell membrane. The protein was detected in fetal tissues and certain types of adult skin cells that are consistent with the pathology of EDA. The function of this protein still remains unknown.2Symptoms and ProgressionBefore a fetus is large enough to be seen, a thin laye...
